It is the purpose of this project to delineate at the molecular and cellular level the mechanism of action of microbial components in immunopotentiation. In the past year, four major efforts have been made: 1) chemical synthesis and isolation of analogs of trehalose mycolates, 2) characterization of the biological activity of these analogs, 3) quantitative determination of the molecular interaction of these analogs with endotoxic glycolipids, and 4) determination of the nature of the cellular immunological response to tumor cells following treatment of tumor-bearing animals with anti-tumor active microbial components.